An advantage of dry stack masonry systems is that the labor component of installation can be dramatically reduced. Some studies have shown that dry stack masonry systems are up to ten times faster to install than conventional joint mortared masonry systems. Because these systems do not use bonding mortar to provide joint support, it may be necessary to use other means of developing wall strength.
One technique to develop wall strength is to pour wet concrete or grout into the openings of the block to form vertical posts. The wet concrete is poured into the open cells of the concrete block. Various building codes may require dry-stacked concrete block cells to be filled differently in order to provide specified structural integrity. Some applications may require all the cells to be filled with concrete. Other applications may require the concrete to be poured into distinct vertical columns and only in certain cells or cores of the block. These applications may require cells, for example, to be filled generally at four foot on center increments and/or at wall corners and jambs of windows and doors or various load points. A general overview of the use of current dry stack methods in masonry wall construction can be found in National Concrete Masonry Association's (NCMA) technical publication TEK 14–22 “Design and Construction of Dry-Stack Masonry Walls.”
The vertical posts are typically reinforced with reinforcement members, for example, steel rebar. The problem with many dry stack block systems is that when stacked, the cells or core holes of the block are not completely aligned. The cells between successive layers of block may vary in size as shown in FIGS. 1A and 1B. FIGS. 1A and 1B show a stack of a conventional dry block system 100. The middle row 102 provides a narrow passage 104 relative to the top row 106 and bottom row 108. When concrete is poured in the cells the variation in cell dimensions may hinder or prevent reinforcement members from being inserted in the cores to form the vertical posts. In addition, the variation in cell dimensions may make it difficult to fill the voids within the cell. Many conventional dry stack block systems may provide little or no damming capacity when filling the cells of a dry stack block wall structure.
The current dry stack wall systems used in building construction for load bearing and non-load bearing walls that incorporate raised lugs for alignment and interlocking do not provide adequate or uniform core orientation, as previously discussed. Additional descriptions of prior art raised lug systems are disclosed in U.S. Pat. No. 3,968,615 to Ivany, U.S. Pat. No. 4,182,089 to Cook, and U.S. Pat. No. 4,640,071 to Haener.
When stacked in a running bond, a core block resting on top of two halves of a lower adjacent block, the lack of uniform orientation of prior art systems fail to provide a uniform and well-aligned core for forming concrete posts. The prior art dry-stack block systems require lugs that project above the top surface of the block. These lugs tend to limit where blocks can be stacked in relation to one another. In addition, the prior art alignment of lugs prevents the stacking of blocks in a single stack bonded configuration (one block resting completely on top of a lower adjacent block).